Comparative effectiveness of chemical insecticides against the chilli thrips, Scirtothrips dorsalis Hood (Thysanoptera: Thripidae), on pepper and their compatibility with natural enemies

The chilli thrips, Scirtothrips dorsalis Hood, is a significant pest of various vegetable tropical fruit and ornamental crops. Originally from south Asia, this pest is becoming widely distributed in tropical, subtropical and temperate areas, and in 2003 was found for the first time in the Western Hemisphere established on St. Lucia and St. Vincent in the insular Caribbean. Since there is a paucity of information on the effectiveness of modern insecticides in managing S. dorsalis populations, we evaluated the efficacy of the following insecticides for their control of this pest on ‘Scotch Bonnet’ pepper on St. Vincent: spinosad, imidacloprid, chlorfenapyr, novaluron, abamectin, spiromesifen, cyfluthrin, methiocarb, and azadirachtin. Irrespective of the number of applications and use of surfactant, chlorfenapyr was the most effective in reducing the densities of S. dorsalis adults and larvae followed by spinosad and imidacloprid. The performance of other insecticides in controlling S. dorsalis populations was inconsistent. Nevertheless, all of the above insecticides if applied repeatedly were effective in suppressing of S. dorsalis populations. Addition of the surfactant-sticker, Nu-Film 17™, improved the performance of all insecticides somewhat. Spinosad was slightly harmful and chlorfenapyr was moderately harmful to Cryptolaemus sp. predators.